def get_formatted_name(first_name,last_name):
    """返回全名。"""
    full_name=f"{first_name} {last_name}"
    return full_name.title();

print(get_formatted_name('zhang','san'))

def get_formatted_name(first_name,middle_name,last_name):
    full_name=f"{first_name} {middle_name} {last_name}"
    return full_name.title();

print(get_formatted_name("zhang","guan","san"))